Process for the production of molded objects



Nov. 18, 1969 G. KARDAUN ET AL 3,479,251

PROCESS FOR THE PRODUCTION OF MOLDED OBJECTS Filed Aug. 13, 1965 United States Patent 3,479,251 PROCESS FOR THE PRODUCTION OF MOLDED OBJECTS Georg Kardaun, Stein, and Hubertus H. Smeets, Spaubeek, Netherlands, assignors to Stamicarbon N.V., Heerlen, Netherlands Filed Aug. 13, 1965, Set. N0. 479,588 Claims priority, application Netherlands, Aug. 18, 1964,

6409480 Int. Cl. C101 5/02; Cb 55/04, 45/02 us. (:1. 201-5 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to improvements in a process for the production of molded objects, such as fuel briquettes and the like. More particularly, the invention relates to an improved apparatus and process for substantially eliminating entrainment of objectionable tar residues in gases evolved during hot mixing of materials to be molded.

The invention has for an object, the more efficient use of gases evolved from the elevated temperature treatment of solids containing volatile matter. The invention has for another object the elimination of entrained tar residues from such evolved gases so as to greatly reduce or substantially eliminate the formation of troublesome d eposits and encrustation that now lead to line clogging in such systems. Other objects will become apparent as this description proceeds.

The invention is particularly concerned with processes and apparatus for the production of molded objects by mixing plasticizable materials such as coal particles that soften at an elevated temperature, e.g., semibituminous or bituminous coal, with particles of substantially nonplasticizable or nonsoftening materials, to provide a moldable mixture capable of being formed into fuel briquettes or the like molded objects. The substantially nonsoftening particles include particles that do not soften, and particles that hardly soften at the elevated softening temperature of the coal particles. Typical of these nonsoftening particles are low volatile fines, coke breeze or ore, which particles are in the heated state during the process of the invention. The invention also has application to mixing of other materials that can be molded or briquetted, and that evolve gases during heating and mixing.

These molding processes are characterized in that the particles that are to be softened become soft during the hot mixing step by heat transfer from the other particles, whereafter the hot mixture is pressure-molded into objects of the desired shape. Such a process has been described in copending United States patent application, Ser. No. 241,994, filed Dec. 3, 1962, now US. Patent 3,213,169, and the disclosure thereof is incorporated herein by reference.

This copending application describes and claims a process for the manufacture of molded products comprising the steps of: heating a first substance including a desired inert by direct contact with a hot gas flow to a temperature substantially above a predetermined temperature;

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separating the heated first substance from said gas flow; heating a second substance including a plasticizable material by direct contact with the gas flow from which said first substance was separated to a temperature which is below said predetermined temperature and which is insufficient to soften said second material to a significantly tacky condition; separating the heated second substance from the gas flow; mixing the heated first substance which is above said predetermined temperature with the heated second substance which is' below said predetermined temperature; effecting a heat exchange between said heated first and second substances to bring the mixture to said predetermined temperature at which temperature said second substance is sufficiently softened as to constitute a binder for said first substance; and molding said mixture. Preferably, the mixture is molded into fuel briquettes.

According to US. Patent Number 3,213,169, admixing the nonsoftening particles heated to the required temperature, which exceeds the temperature of the: softening coal particles, is done in a mixing vessel or mixing chamber equipped with stirrers, in which vessel the lower-temperature particles that are to be softened become soft through heat-exchange with the hotter non-softening particles. As explained in US. Patent Number 3,213,169 gases are evolved during this process which have been found to contain tar residues and a small amount of entrained fines. The tar containing gases thus released are discharged from the mixing vessel via lines that lead through a suitable scrubbing system. In the scrubbing system, the gases are cooled and freed from any entrained solids. However, the tar residues are not as easily removed but tend to cause deposit build-ups. Hence, the evolved gases are presently objectionable owing to deposit formation and consequent clogging of the lines.

It has now been found that the above mentioned troubles can be obviated if the gases issuing from the mixing vessel, prior to admission to the scrubbing system, are brought into direct contact with the hot, nonsoftening, or hardly softening material to be fed to the mixing vessel. This has the advantage of converting the tar in the gases into products which do not form deposits and hence do not clog the lines.

The improved process according to the invention can be carried out in the installation schematically illustrated in the drawing.

This installation is provided with supply cyclones or reservoirs 1 and 2 for feeding heated materials which are to be molded, as disclosed in U.S. Patent Number 3,213,169 mentioned above. Feed screws 3 and 4 and feed ducts 5 and 6 may be employed to conduct or supply separate streams of the heated materials from the respective reservoirs 1 and 2 to the mixing bunker or mixing chamber 8, which is preferably shaped to be free of dead corners. Mixing may be accomplished as in U.S. Patent Number 3,213,169, or simply with the horizontal stirrer shown. The mixing vessel terminates at an ordinary feeding or metering device 9 which in turn leads to the roll press 10. The latter may be of the known briquetting type.

Feed duct 5 is open at the upper end so that gases evolved in the mixing chamber may be exhausted through the riser 11, scrubber system and feed line 12, and into the wash trough 13, for final cleaning before being exhausted up through the line 14.

According to the invention, reservoir 1 contains the heated nons-oftening material and reservoir 2 contains the coal to be softened, respectively. The feed screws 3 and 4 continuously supply material from the reservoirs 1 and 2, via the lines 5 and 6, to the top of mixing vessel 8, which is provided with a shaft 7 carrying stirrer arms. From the mixing vessel, the mixture gravitates into a feeding device 9, which supplies it to the roll press 10.

The gases released in the mixing vessel escape through pipe 5, where they come into contact with the hot nonsoftening material supplied from reservoir 1. Thereafter, the gases flow on to riser 11 connecting to the scrubbing system, which comprises a line 12 and a wash trough 13.

Water from line 15 is sprayed through the branch lines shown at several places into line 12, as a result of which the gases are cooled and washed free of dust. The cleaned gases flow off through line 14. The wash water is sewered via line 16.

In accomplishing its objectives, the invention provides a substantial improvement in preventing deposit formation and line clogging in the riser and scrubber. For example, it has been found according to US. Patent Number 3,213,169, that briquetting at a rate of two tons coke breeze, six tons dry, nonvolatile fines, and two tons dry bituminous lines per hour will produce approx. kg. per hour of tar deposit in the riser and scrubber lines. In continuous operation, clogging becomes severe enough in 1-2 days to require a shutdown for cleaning. On the other hand, the present invention reduces the tar deposit to such a low level that it almost completely eliminates the need for shutdown between ordinary repair periods which ocour every 6 weeks.

It will be understood by those in the art that a preferred embodiment has been disclosed forpurposes of illustration, and that the invention may be subject to modifications and variations without departing from the scope of the appended claims.

What is claimed is:

1. In a process for the production of molded fuel briquettes and the like, comprising the steps of hot-mixing coal particles softening at elevated temperature with heated particles that are substantially nonsoftening at said elevated temperature, wherein the heated particles that are nonsoftening are heated to a temperature which is above the temperature wherein the mixed coal particles that are capable of softening becomes soft, and tar containing gases are evolved, whereafter the hot mixture is molded into fuel briquettes and the like, the improvement comprising bringing the released gases into contact with the hot nonsoftening particles prior to the hot mixing step, so that entrained tar is substantially converted into products that do not clog the lines through which said gases are removed.

2. In a process for the production of molded fuel briquettes and the like, comprising: supplying a stream of coal particles that will soften at an elevated temperature, supplying a stream of particles that are substantially nonsoftening at said elevated temperature, heating said substantially nonsoftening particles to at least said elevated temperature, and then mixing said coal particles with said substantially nonsoftening particles so that a transfer of heat is effected to heat the coal particles enough that coal particles capable of softening become soft, and tar containing gases are evolved from the heated coal particles, followed by molding the mixed particles into fuel briquettes and the like, the improvement comprising bringing the evolved tar-containing gases into contact with the heated and substantially nonsoftening particles prior to the mixing step so that the properties of the entrained tar are changed by said contact with the heated nonsoftening particles so that the evolved gases, will be substantially free of deposit forming products that clog surfaces with which said evolved gases come into contact.

3. The process of claim 2 wherein the heated and substantially nonsoftening particles are moving vertically downward and wherein the tar containing evolved gases rise vertically upward such that the substantially nonsoftening particles and evolved gases are in counter-current flow.

4. The process of claim 2 wherein the coal particles are selected from the group consisting of particles of bituminous coal and semibituminous coal.

5. The process of claim 2 wherein the substantially nonsoftening particles are selected from the group consisting of low-volatile fines, coke breeze and ore.

References Cited UNITED STATES PATENTS 2,582,712 1/1952 Howard 20128 X 2,922,752 1/1960 Reintjes 20l3 X 3,085,947 4/1963 Tufty 201l2 X 3,167,487 1/1965 Mansfield 20129 X 3,174,846 3/1965 Brisse et al. 75--3 REUBEN FRIEDMAN, Primary Examiner R. W. BURKS, Assistant Examiner US. Cl. X.R. 

